In the prior art, as shown in FIG. 1, a flash tank includes a flash chamber 1′, and a flash tank liquid inlet 11′ and a flash tank liquid outlet 12′, located in one side of the flash chamber 1′.
High-temperature and high-pressure liquid refrigerants coming from a condenser enter the flash chamber 1′ by the flash tank liquid inlet 11′, a small number of liquid refrigerants become air under an action of flash evaporation, the air enters a compressor by an air replenishment opening 13′ and is compressed again, and meanwhile, certain heat is absorbed, so the temperature of the remaining liquid refrigerants drops, and the remaining liquid refrigerants enters an evaporator via the flash tank liquid outlet 12′ finally. The above-mentioned flash tank has the following defects.
(1) The flash tank has only one air replenishment opening 13′, and requirements of a multi-stage compressor and a multi-stage air replenishment unit cannot be met.
(2) The flash tank does not have a throttle device, thereby is difficult to accurately control the flow of air discharged from the air replenishment opening 13′.